10 Doctor Who Moments You Didn't Get As A Kid (But Do As An Adult)

Only the most precocious of children would've had the working knowledge of Agatha Christie that's required to recognise the myriad references to the legendary author's work in The Unicorn and the Wasp.

There are over a dozen references to Christie's novels peppered throughout the script, and even in the set design – for example, a vase of yellow iris flowers on the table during the group dinner scene serves as a reference to the Hercule Poirot short story Yellow Iris.

Russell T Davies and Gareth Roberts delighted in adding as many references to Christie's body of work into the dialogue as they could. There are obvious ones, such as Donna remarking "the body in the library", upon discovering the body of Professor Peach in the library, which is a nod to Christie's 1942 novel The Body in the Library. But there are deeper cuts too.

Sparkling Cyanide, Taken at the Flood, Appointment with Death, and Dead Man's Folly – all titles of Agatha Christie stories, and all spoken out loud throughout the course of the episode. There are so many of these references scattered across The Unicorn and the Wasp that even the adults may struggle to keep up, and the kids, meanwhile, would've had no chance.

It's only upon growing up and being more inclined to familiarise yourself with Christie's work that these puns become more apparent.